Adult cardiomyocyte does not almost grow, and thus the lack of cardiomyocytes caused by ischemic heart disease or the like becomes an irreversible damage. At present, there are no clinically used medicines or treatments that exhibit efficacy in substitution of a myocardial scar with a functional contractile tissue. Hence, novel therapies for the regeneration of normal cardiomyocytes are highly desired. A replacement therapy that involves the administration of separately produced cardiomyocytes has been proposed. In connection with such replacement therapy, administration of cardiomyocytes that are sheet-shaped so as to enable successful engraftment of the cells to the heart of a recipient has been examined (Non-patent Literature 1, Patent Literature 2). However, because this therapy is problematic in that the cell amount in such a sheet is insufficient and thus therapeutic effects cannot be obtained as expected, it is suggested that the sheets should be laminated before administration (Non-patent Literature 2).
Meanwhile, methods of using fetal cardiomyocytes, myoblasts, cardiac myoblasts generated from adipose tissue-derived stem cells and embryonic stem cell-derived cardiomyocytes, have been exemplified as supply sources of cardiomyocytes for sheet preparation (Patent Literature 2, Non-patent Literature 3).
However, there has been no report that cardiac functions were improved as a direct effect by administration of sheets formed only from embryonic stem cell-derived cells.